1. Field of the Invention
The present invention relates to a device and method for the prevention and/or treatment of osteoporosis, fractures of the hip, spine fractures, and/or spine fusions using inductively coupled electric fields generated by coils inserted into a patient's undergarments and powered by a portable power source.
2. Description of the Prior Art
As previously reported in U.S. Pat. No. 4,467,808, issued Aug. 28, 1984, and as reported in three published papers by Brighton et al (Bone, 6:87–97, 1985; J. Orthopaedic Research, 6:676–684, 1988; and J. Bone and Joint Surger, 71A: 228–236, 1989) an appropriate capacitively coupled electric field prevented and/or reversed osteoporosis induced in the rat vertebra or tibia. It has also been previously reported in U.S. Pat. No. 4,535,775, issued Aug. 20, 1985, and in several published papers by Brighton et al (J. Trauma, 24:153–155, 1984; J. Orthopaedic Research, 3:331–340, 1985; and J. Bone and Joint Surgery, 67A: 577–585, 1985) that an appropriate capacitively coupled electric field increased the rate of healing in fresh fractures in the rabbit fibula and healed human fracture nonunions at a rate comparable to that of bone graft surgery (Clin. Orthop. And Related Research, 321: 223–234, 1995). Lastly, it was reported recently that an appropriate capacitively coupled electric field used as an adjunct to lumbar spinal fusion significantly increased the rate of fusion when compared to patients who had spinal fusion without electrical stimulation (Goodwin, Brighton, et al, Spine, 24:1349–1356, 1999).
All of the above studies used capacitive coupling, a method of noninvasively producing an electric field in tissues within the body such as bone and cartilage. Capacitive coupling, as used in those studies, requires the use of a pair of electrodes attached to the surface of the patient's skin adjacent to or near the location of treatment. Capacitive coupling is a very convenient, patient “friendly” method of applying electricity to the patient in the treatment of bone fractures, nonunions, bone defects, and localized lumbar spine fusions. However, capacitive coupling is not a practical way of treating multiple segment spine fusions or to treat a relative large area. This limitation of capacitive coupling led the present inventors to invent a method and device for achieving the same internal electrical fields in vertebrae at multiple levels by using either multiple electrode pairs or by using strip electrodes, as described in U.S. Provisional Patent Application No. 60/302,846. The multiple electrode pairs or strip electrodes (one long electrode on either side of the spine) described therein are designed to be worn 24 hours per day and to be changed periodically for a treatment period of, e.g., 8–12 weeks.
The present inventors also set out to extend the techniques described in the above-mentioned patents and articles to the treatment of osteoporosis, fractures of the hip or spine, and/or spine fusions in humans. However, the present inventors soon discovered that transferring existing data to the application of electric signals to the human spine and hips in patients with osteoporosis, fractures of the hip or spine, and/or spine fusions was far from straightforward. A determination of the proper electric field amplitude and method of applying electricity to the patient for the treatment of osteoporosis, fractures of the hip or spine, and/or spine fusions needed to be developed. Capacitive coupling was substantially eliminated as a method of producing an electric field in the spine to treat osteoporosis because family assistance is required to apply the electrodes. Such assistance is frequently unavailable in this generally older patient population afflicted with osteoporosis and hip and spine injuries. Moreover, such patients typically will require the application of electric fields for months to years and possibly for the duration of the patient's life.
Accordingly, it is desired to develop an equivalent electric field in vertebrae and other bones and tissues, such as the hip, as achieved with capacitive coupling, except that it is desired to use only electromagnetic fields instead of capacitively coupled fields so that electrodes will not need to be applied to the patient. Inductive coupling devices will create the opportunity for the development of garments and the like that can be readily applied to the treatment area by the patient. The present invention addresses the features of such garments.